i have long used lucas oil stabilizer with fantastic results.. when i bought my 2005 ford deisel i was concerned about using additives , due to all the controversy around these engines.. i used the fuel treatment when i guy i know praised it highly to me.. being a lucas fan if figured it couldnt hurt .. i noticed no fuel milage increases , but did notice better performance & quieter running from the motor.. i have used it every fill up since & recomend it to anyone with a deisel engine.. i have had a bottle of the synthetic oil stabilizer recomended for these 6.0 engines sitting on a shelf in my shop for 6 months.. fearing to use any additive in the motor.. after searching for info. on this site i added it today at my oil change .. i expect good results & will let you know .. i dont care about extended fuel mileage.. my concerns only go to whats best for the engine.. these trucks arent cheap.. i expect the results will be as good as the fuel treatment was..